Exemplary embodiments herein generally relate to a side curtain airbag, and more particularly, to an automated vision inspection of a side curtain airbag assembly for detecting whether a cushion of the side curtain airbag assembly is in a twisted state at the time of installation.
The side curtain airbag assembly is a safety device applied to passenger vehicles and is deployed by inflation with a pressurized gas to protect the occupants of the vehicle from a side impact head injury and to resist ejection from the vehicle in the case of a rollover. Generally, the side curtain airbag assembly includes a cushion, an inflator, mounting hardware and a variety of other hardware based on the requirements of the application. When the side curtain airbag assembly is manufactured, the cushion is rolled or folded to minimize the space occupied by the device in the vehicle. In some designs, the rolled or folded cushion is covered by a tubular sleeve of material which has a sewn seam or perforated line which ruptures when the inflation of the cushion begins. The side curtain airbag assembly is installed in a manner that the device begins generally at the base of the A-pillar (front), up the A-pillar, along the length of the roof, down the rear pillar (B, C or D pillar) and ends at the rear of the passenger compartment. In the simplest arrangement, the side curtain airbag assembly is long (two to four meters), slender (30 to 120 millimeters in circumference), and quite flexible (bend and twist). Due to this flexibility characteristic, installation must be done carefully to ensure the side curtain airbag assembly is not mounted to the vehicle with a 360 degree twist imparted to the longitudinal axis of the cushion. A twisted cushion may not deploy properly and thus may not provide the desired passenger safety protection.
To ensure proper installation, various vehicle manufacturers have applied markings to the cushion and/or sleeve to make a twisted installation more easily recognized with the human eye. Other manufacturers have employed hardware added to the side curtain airbag assembly to make imparting a 360 degree twist more difficult. In some cases, the additional hardware is extensive and thus adds weight and cost to the side curtain airbag assembly. Therefore, it is desirable to eliminate such weight and cost as long as other measures are taken to ensure a proper installation of the side curtain airbag. Automated vision inspection offers the possibility of such protection, but due to the flexible and compliant nature of the side curtain airbag assembly, the technology is prone to false detections. False detections are disruptive to manufacturing operations and thus resistance to application of vision inspection technology exists.
Automated vision inspection involves the capture of digital images of the installed side curtain airbag assembly and processing those images through imaging processing software that has been programmed to look for key features previously defined and to assess the installed condition by comparison of the current image to a master image. Due to the flexible and compliant nature of the side curtain airbag assembly, each installation is unique and thus, the master image would only give a satisfactory judgment when compared to itself. Therefore, for automated inspection, it is important to provide the image processing software with feature that can be easily detected within the digital images and evaluated for presence, position and orientation and subsequently used to determine the installed condition, twisted or not twisted, of the side curtain airbag assembly.
Traditional markings on the side curtain airbag assembly such as stripes, writing (in any language) or barcodes have been used to assist the human eye in detecting twists, but these marks fail to reliably prevent misinterpretation of features in the image when utilizing an automated vision inspection system. For example, in the case of a longitudinal stripe, the two dimensional appearance of the edge of the stripe can appear similar to the edge of the side curtain airbag against the vehicle body. Likewise, the shadow cast by the side curtain airbag can appear as a stripe. Also, the edge features of the vehicle, such as a door opening, can create a line that can be misinterpreted as a cushion stripe. Further, writing on the cushion of the side curtain airbag can create different possibilities of misinterpretation. For example, and as depicted in FIG. 28, consider a cushion with a series of letters or words printed on its entire length. A twisted installation of the cushion would create a gap in the words or letter string. However, if the words are arranged into a phrase, the natural gap between words can be misinterpreted as gaps created by a twisted installation. And, many Roman letters, such as the letter “S”, have rounded sides. These rounded sides can make determining the bottom and side of the mark difficult and therefore determining orientation can be difficult. Still further, if a barcode is printed over the length of the side curtain airbag assembly and the vision system is programmed to read the barcode over the entire length, a bracket or tape required for the assembly may cover part of the barcode or a pucker may create an interruption to the barcode. Such a gap in the barcode could be misinterpreted by the vision system. For the application of a marking system to be effective in conjunction with the application of an automated vision inspection system, the marking system must be robust in order to ensure successful detection and interpretation by the automated vision inspection software. A robust marking system would have the characteristics of being easily detectible and unique within the images acquired while providing the information of position and orientation necessary to inspect the entire length of the side curtain airbag assembly and properly assess the state of the installed assembly. In addition, geometric shapes provided on a length of the side airbag cushion can have issues in interpretation. First, many of these geometric shapes appear in the vehicle in other locations. For example, round, triangular, rectangular and square holes are generally stamped into the vehicle body. Bolts with hexagonal heads, hexagonal pockets or round flanges are used during assembly. If the automated vision inspection system is looking for one of these geometric shapes, the vision system may lock onto a feature in the vehicle rather than the geometric mark on the airbag. Furthermore, as shown in FIG. 14, parallel edges of these shapes can be mistakenly used by the vision system to complete partial shapes. For example, if the right edge of the left hand triangle were missing due to a part covering it, the left edge of the right hand triangle could be used to complete the shape of the left hand triangle.